There is a legal battle in the making that could define the future of digital privacy in the United States. During its investigation of the San Bernardino mass shooting, the FBI got its hands on the shooter's iPhone, which is locked down so securely that the Bureau can't get in to see what's inside. Its solution is to force Apple to open the device, creating a backdoor that would compromise the security of every iPhone everywhere. It's a chilling solution Apple is revving itself up to fight, as CEO Tim Cook outlined in a public letter published this morning.

Cook's letter mentions that the core of the coming fight is the All Writs Act of 1789, a centuries-old federal statue that the FBI is using as its legal backing for the case against Apple. But what is this law, how does it work, and why is a 227-year-old law about to decide the fate of encryption in 2016?

You can't surrender what you don't have

Writ's a Trap

Before we get into the legal nitty gritty, here's a quick rundown of the case at hand. The iPhone in question was owned by Syed Farook, one of the San Bernardino shooters, and is locked and encrypted. Without that specific iPhone's unique decryption key, there's no way to translate the phone's data from complete gibberish back into something coherent. The FBI, which is investigating the case, has a warrant for the information on this phone, but they can't read it.

Farook is dead, so there's no getting the key from him, and Apple doesn't have it either. The company specifically designed its encryption system to keep these keys out of its hands, precisely so that no amount of hacking could steal them and no legal orders could compel Apple to hand them over. You can't surrender what you don't have!

As a result, the FBI has been reduced to its only possible solution: guessing. It wants to just guess codes until it gets it right. The problem is, Apple designed its security system so that too many incorrect guesses can wipe a phone's data—a safeguard designed with professional brute-force passcode guessers in mind. The FBI wants Apple to write a workaround that basically turns this feature off, and it argues it will use the backdoor only on this particular phone. Apple doesn't want to comply, and Cook argues that once this workaround is out there, it is out there. Such a backdoor would work on any phone. There's no putting the genie back in the bottle.

This is where the All Writs Act of 1789 comes in.

The bit of text that's doing the heavy lifting here is quite small, only a sentence. It reads:

The Supreme Court and all courts established by Act of Congress may issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principles of law.

A writ, by the way, is basically just a formal order, in modern usage usually one that's issued by a court. Basically, it's a sweeping legal gesture that gives courts the authority to issue orders compelling people to do things, so long as it's for a legal and necessary reason.

Sounds like a big, broad statute? It is, and that makes sense considering the act was a part of the Judiciary Act of 1789, adopted during the very first session of the very first United States Congress and signed into law by President George Washington himself. The Judiciary Act created the Great Maw of Justice, and the All Writs Act is one of its many teeth.

Extraordinary Situations

As Jonathan Mayer—lawyer and PhD candidate in Computer Science at Stanford University—explains, writs were historically very common, but in recent centuries the All Writs Act generally has a more narrow application. Typically, it's only used in established or extraordinary situations. Limits set by the Supreme Court mean such writs can be used exclusively in situations where there is no other statute or rule that applies to a situation, and can't be used to get around other, existing laws. The shooter's iPhone passcode is certainly an extraordinary situation, which explains why a law from 1789 at play in a case about smartphones.

Now What?

While Tim Cook has come out with a lengthy and well-argued statement that bypassing encryption in the way the court is asking is very dangerous, Apple hasn't made any public moves to fight the order yet. The guns are out, but they aren't blazing yet. However, the Electronic Frontier Foundation, a international non-profit digital rights group, has expressed its interest in helping Apple fight the thing and plans to file an amicus brief in support of Apple's position.

The All Writs Act, while pretty broad, is not all-powerful. The very ruling that orders Apple to help the FBI has a caveat of "unreasonable burden" that's baked into the All Writs Act:

To the extent that Apple believes that compliance with this Order would be unreasonably burdensome, it may make an application to this Court for relief within five business days of receipt of the Order.

The case that restructuring the very nature of iOS just for the FBI's benefit is an unreasonable burden is probably a case Apple could make (and its one the EFF has argued in the past). But this particular legal fight looks like it could blow up to a scale much larger than that particular point. For now there's no telling what the outcome of a clash between Apple and the FBI over a 227-year old will be, but it will almost certainly affect the legal status of encryption in the United States for years and decades to come.

A Part of Hearst Digital Media
Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites.